Wilms (nephroblastoma) accounts for 87% of paediatric renal masses. Its peak incidence is at 3–4 years of age, 80% of patients present before 5 years . It arises from mesodermal precursors of the renal parenchyma (metanephros). Chromosome 11 (WT1: 11p13, WT2: 11p15), loci on chromosomes 1, 8, 12 affection are found. Most cases are sporadic, 2% of cases are familial. They are unilateral in 95 % cases. Some familial syndromic associations are Beckwith Wiedemann, WAGR, Drash syndrome .
Patient presents with painless abdominal mass and haematuria.
On plain abdomen X-ray a large soft tissue opacity is usually seen displacing the bowel inferiorly. Ultrasound confirms the solid nature of the mass, distinguishes it from hydronephrosis and cystic renal masses. Doppler assesses renal vein, IVC for tumour thrombus. CT/MRI are needed for accurate staging . On CT they appear as intrarenal heterogeneously enhancing solid masses surrounded by a compressed rim of renal parenchyma. They displace adjacent structures like aorta and its branches without encasing/invading them. When large these tend to cross the midline. Tumour thrombus may extend into the renal vein, IVC, right atrium. Calcification, fat may be seen rarely. MRI assesses IVC involvement accurately. It metastasizes most commonly to the lung (85%), liver, lymph nodes. Bony metastases are very rare in Wilms tumour and are associated with a poorer prognosis .
Staging is surgical (National Wilms tumour study group). Stage I (confined to kidney), II (extension beyond kidney but limited capsular, renal vein, sinus involvement, completely resected) are treated by combination of chemotherapy to downstage the tumour followed by resection (complete nephrectomy). Stages III (lymph nodal, peritoneal spread, incomplete resection), IV (haematogenous, lymph nodal metastastes outside abdomen) are treated with chemoradiotherapy. In Stage V (synchronous bilateral) preoperative chemotherapy is important. Complete resolution of disease in one kidney may allow surgery on the contralateral kidney. Each kidney is staged individually, followed by partial nephrectomy. Local radiation therapy of the tumour bed is advocated in some cases, complete abdominal irradiation can be used when there is gross tumour spillage at surgery or peritoneal tumour implantation . Recurrence can be within the tumour bed, as well as distally.
Our patient, with stage IV Wilms, underwent nephrectomy followed by chemotherapy (actinomycin-D, doxorubicin, cyclophosphamide, carboplatin, etoposide) for 6 weeks, radiotherapy to abdomen and thorax. Unfortunately during the chemotherapy, the patient succumbed to chest infection. From the overall clinical course of the patient we could conclude that bony metastases in Wilms are a poor prognostic factor.